ISL97651ARTZ-TK Intersil, ISL97651ARTZ-TK Datasheet - Page 15

• Manufacturer Part Number: ISL97651ARTZ-TK
• Description: IC LCD SUPPLY HP 4CHN 36-TQFN
• Manufacturer: Intersil

Specifications of ISL97651ARTZ-TK

• Applications: LCD TV/Monitor
• Current - Supply: 400µA
• Voltage - Supply: 4 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 36-TQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Negative Charge Pump Design Consideration
The negative charge pump consists of an internal switcher
M1, M2 which drives external steering diodes D2 and D3 via
a pump capacitor (C12) to generate the negative V
supply. An internal comparator (A1) senses the feedback
voltage on FBN and turns on M1 for a period up to half a
CLK period to maintain V
0.2V. External feedback resistor R6 is referenced to V
Faults on V
are detected by comparator (A2) and cause the fault
detection system to start a fault ramp on C
cause the chip to power down if present for more than the
time TFD (see "Electrical Specification" on page 2 and also
Figure 15).
The maximum V
pump is:
V
OFF_MAX
(
OFF
2x
)
=
which cause V
–
OFF
1.2MHz
V
SUP
0.9V
VREF
output voltage of a single stage charge
+
V
(FBN)
DIODE
15
FBN
in regulated operation at
+
2 I
•
to rise to more than 0.4V,
FB
Error
OUT
Control
( •
DLY
r
ON
(
FIGURE 13. V
NOUT
pin which will
OFF
)H r
(EQ. 19)
REF
+
VSUP
ON
.
ISL97651
M1
ON
(
NOUT
FUNCTION DIAGRAM
VSUP
VSUP
D3
)L
M3
M5
M2
M4
R6 and R7 in the “Typical Application Diagram” on page 10
determine V
Improving Charge Pump Noise Immunity
Depending on PCB layout and environment, noise pick-up at
the FBP and FBN inputs, which may degrade load regulation
performance, can be reduced by the inclusion of capacitors
across the feedback resistors (e.g. in the “Typical Application
Diagram” on page 10, C21 and C22 for the positive charge
pump). Set R6 • C20 = R7 • C19 with C19 ~ 100pF.
V
OFF
D2
=
V
FBN
D1
OFF
•
⎛
⎝
output voltage.
1
+
C1-
C1+
POUT
C2+
C2-
FBP
R7
------- -
R6
⎞
⎠
–
V
C21
REF
C22
C7
C8
•
⎛
⎝
C14
External Connections
R7
------- -
R6
and Components
⎞
⎠
R8
R9
x2 Mode
x3 Mode
Both
April 24, 2009
(EQ. 20)
FN7493.3